edit: It looks like there's a problem here only with featureFlagDualCatalogCache specified. de-escalating and we'll dig in more.

previous description (where we thought we needed a critical advisory):
For this special codepath, it looks like there is no mechanism to allow the shard servers to detect that the collection is sharded - they will send a request to the primary shard for the db (b/c they default to assuming it's unsharded), and the primary shard for the db will see the storedSource option and fail to perform any shard versioning protocol checks - completing the request successfully instead of returning the error which would indicate the collection is sharded.